Geochemistry and petrology of the Early Miocene lamproites and related volcanic rocks in the Thrace Basin, NW Anatolia


Ersoy Y. E. , Palmer M. R. , UYSAL İ. , Guendogan I.

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH, cilt.283, ss.143-158, 2014 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 283
  • Basım Tarihi: 2014
  • Doi Numarası: 10.1016/j.jvolgeores.2014.06.016
  • Dergi Adı: JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
  • Sayfa Sayıları: ss.143-158

Özet

The extensional Thrace basin (NW Anatolia) contains an association of early Miocene diopside-leucite-phlogopite (Doganca) and diopside-phlogopite (Korucukoy) lamproites with Oligocene medium-K calc-alkaline andesites (Kesan volcanics), early Miocene shoshonitic rocks (Altinyazi trachyte) and middle Miocene Na-alkaline basalts (Begendik basalts). The Doganca lamproite (K2O = 5.1-5.5 wt.%; K/Na = 2.78-2.89; MgO = 11.4-11.8 wt.%) consists of olivine (Fo(71-86)), diopside (Al2O3 = 1.0-5.0, Na2O = 0.2-0.6), phlogopite (TiO2 = 1.1-9.4, Al2O3 = 11.1-13.9), spinel (Mg# = 22.9-32.6; Cr# = 64-83.4), leucite, apatite, zircon, Fe-Ti-oxides and magnetite in a poikilitic sanidine matrix. The potassic volcanic units (lamproites and trachytes) in the region have similarly high Sr and low Nd isotopic compositions (Sr-87/Sr-86((i)) = 0.70835-0.70873 and Nd-143/Nd-144((i)) = 0.51227-0.51232). The major and trace element compositions and Sr-Nd-Pb isotopic ratios of the shoshonitic, ultrapotassic and lamproitic units closely resemble those of other Mediterranean ultrapotassic lamproites (i.e., orogenic lamproites) from Italia, Serbia, Macedonia and western Anatolia. The Begendik basalts show intraplate geochemical signatures with an Na-alkaline composition, an absence of Nb negative anomalies on primitive mantle-normalized multi-element diagrams, as well as low Sr (similar to 0.70416) and high Nd (0.51293) isotopic ratios; and include olivine (Fo(72-84)), diopside, spinel, Fe-Ti-oxides and magnetite.